1. Field of the Disclosure
The present disclosure relates generally to a user equipment in a mobile communication system and a control method thereof and, more particularly, to a user equipment that can prevent throughput degradation of a mobile communication system due to a mismatch of security states between the user equipment and a base station.
2. Description of the Related Art
Recently developed mobile communication systems may include a long term evolution (LTE) system or a universal mobile telecommunication system (UMTS) in a high speed data communication service (e.g., the 3rd generation partnership project (3GPP)), which wirelessly provides various multimedia services.
FIG. 1 is a diagram illustrating a security authentication procedure between a user equipment and a base station in a mobile communication system (e.g., the UMTS system) proposed in the 3GPP.
Referring to FIG. 1, a base station (BS) 110 transmits a security mode command message to a user equipment (UE), in step 120, in order to exchange security information. The security mode command message may include ciphering information and integrity information.
When the security mode command message is received from the BS 110, the UE 100 may configure the ciphering information and the integrity information (e.g., a key value and/or algorithm type) included in the security mode command message. The UE transmits a security mode complete message to the BS 110, in step 130.
When the security mode complete message is received from the UE 100, the BS 110 transmits a response (e.g., an L2Ack in a layer 2 level) to the security mode complete message to the UE 100, in step 140. When the response (e.g., the L2Ack) has been received from the BS 110, the UE 100 may determine that the security authentication procedure is completed. Further, the BS 110 may determine that the security authentication procedure is completed at a time when the response is transferred to the UE 100.